1. Technical Field
Embodiments of the subject matter disclosed herein generally relate to sealing electrical connectors, and more particularly, to a sealing electrical connector between a first down hole tool portion and a second down hole tool portion of an oil well survey tool.
2. Discussion of the Background
Down hole survey tool strings are made up of a series of discrete tool portions which are connected together as the survey tool is advanced into the ground. Feed through connectors are employed to facilitate the delivery of an electrical signal from one tool portion to the next without allowing high pressure fluid to enter the string at the connection between adjacent tool portions.
FIG. 11 shows a typical feed through connector 714 seated in a tool portion 720. Feed through connector 714 includes a body 716 having a channel 718 for an O-ring 722. The O-ring 722 seals between the connector body 716 and a seat 728 in the tool portion 720. Connector 714 further includes a contact pin 724 and a glass insulator 726 between the contact pin 724 and the body 716. During fabrication of the connector 714, the glass insulator 726 is melted into place to provide a seal between the contact pin 724 and the body 716.
Although not shown, a first line from a first down hole tool portion connects to the down hole end of the contact pin 724 and a second line from a second tool portion connects to the other end of the contact pin 724. During use, high pressure fluid in the down hole environment (to the left of pin 724 in FIG. 11) is prevented from penetrating into the internal area (to the right of pin 724 in FIG. 11) of tool portion 720 by O-ring 718 and glass insulator 726.
FIG. 12 shows another feed through connector 814. Connector 814 represents a type of connector such as is manufactured by Kemlon Products Company of Houston, Tex. and includes a connector body 816 having a channel 818 for an O-ring 822. Although not shown, body 816 and seat 828 may include threads for connecting body 814 to tool portion 820. A contact pin 824 extends through the body 816 and a glass insulator 826 seals between contact pin 824 and body 816. Body 816 also includes a flange 832 and a ridge 834. In another embodiment (not shown), body 816 is made of polyether ether ketone (PEEK) which is molded around contact pin 824.
Connector 814 further includes a slip-on boot assembly 836 including a rubber boot 838 and a radial groove 840, an insulating sleeve 842, and a socket connector 844. Rubber boot 838 and insulating sleeve 842 are slipped over insulated wire 846. The hole 848 in the end of the rubber boot is sized slightly smaller than the outside diameter of the insulated wire 846 to compress onto the wire to provide a low pressure seal. The end of the insulated wire 846 is then stripped of insulation to allow the wire to be soldered into one end of the socket connector 844. Insulating sleeve 842 is then slid over socket connector 844 and rubber boot 838 is slid over sleeve 842 to complete the assembly of boot assembly 836.
The boot assembly 836 is then pushed onto connector 814 causing the free end of socket connector 844 to engage contact pin 824 and radial groove 840 to engage ridge 834. In use, pressure in the down hole environment increases the sealing force of rubber boot 838 against wire 846 and ridge 834 by contact of surfaces of hole 848 and groove 840, respectively.
One problem associated with connector 714 (FIG. 11) is that contact pin 724 extends outwardly from both ends of glass insulator 726. This renders the pin exposed and prone to damage, for example, during contact with components, tools, personnel, etc., or as another example, during operation of the survey tool due to, for example, vibration of the string. Potential damage to pin 724 is aggravated by the dimensions of the pin itself, i.e., the pin is elongated and has a small diameter. The pin is also rendered more vulnerable to damage by the other components of connector 714 in that there is a general lack of shock absorption or cushioning available due, in part, to the rigidity of the pin itself and the brittle nature of the glass insulator 726 and body 716.
As may be appreciated from FIG. 12, connector 814 extends outwardly from the end of tool portion 820 farther than pin 724 and is thus also prone to damage. Further, note that pin 824 is longer than pin 724 and extends even further from tool portion 820 than pin 724 extends from tool portion 720. Thus, pin 824 is even more prone to damage than pin 724.
Moreover, because boot assembly 836 extends outwardly from body 816, space for this assembly must be provided in the adjacent tool portion. The extra machining necessary to create this space is both difficult and expensive. And, the removal of material to accommodate the assembly weakens the tool portions. Further, the extra parts in boot assembly 814 add complexity, increase costs, and present further opportunities for problems to occur during assembly and operation of a survey tool incorporating such parts.
Accordingly, there is a need for an electrical connector that is simple, easy to use, operates with less parts, requires less space, utilizes components that are less brittle, and which is less prone to damage. Moreover, there is a need for an improved sealing connector capable of use between down hole tool portions in an environment having an ambient pressure greater than atmospheric pressure.